Scientific American presents Math Dude by Quick & Dirty Tips. Scientific American and Quick & Dirty Tips are both Macmillan companies.

In How to Make a Graph (Part 1), the infamous hero of our ancient Egyptian plotline, Knot Dude, taught his pyramid-building father, Papa Knot, a quick and dirty method for figuring out the corner-to-corner diagonal length of a pyramid's base. In particular, he taught his dad the very same 4-step method for making graphs that we're learning.

Last time we talked about the first two steps of Knot Dude's method: drawing Cartesian coordinates and creating a list of ordered pairs. As you might expect, today we're going to talk about the final two steps. What are they? And what can we do with the graph we end up with? Stay tuned to find out!

Steps 1 & 2 Review
If you missed the first part of this series, you might just want to stop right now and go take a look at it. Because everything we're going to talk about today is based upon the stuff that Knot Dude taught his father in that episode. In particular, he taught his dad that the first step in making a graph is to draw what's called Cartesian coordinates. What's that you ask? Check out Part 1 of this series to find out!

In that episode, we also learned that the length of the corner-to-corner diagonal across a pyramid's base can be written c = √2•a. Knot Dude told Papa Knot that the easiest way to make his graph is to start by using this equation to calculate the lengths of the diagonals, c, for a bunch of pyramids with different sized bases, a, and then to use his results to make a list of values written like (ac).

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